//从访问地址中获取访问信息
function getParamValue(urlkey) {
    var param=location.search;
    param=param.substring(1);
    var paramArr=param.split('&');
    for (i=0;i<paramArr.length;i++){
        item=paramArr[i].split("=");
        if (item[0]===urlkey)
            return item[1];
    }
    return null;
}